Pressure equalizing breaker point



Feb. 21, 1956 A. c. RUSSELL 2,735,905

RESSURE EQUALIZING BREAKER POINT ASSEMBLY Filed Jan. 17, 1955 INVEN TOR. zi/wdren 6/44? Faasefl ATIUKIVEK United States Patent PRESSURE EQUALIZING BREAKER POINT ASSEMBLY Andrew Craig Russell, Shawnee, Okla. Application January 17, 1955, Serial No. 481,989 6 Claims. (Cl. 20031) This invention relates generally to the field of internal combustion engines and, more particularly, to further improvements over the breaker point assemblies for use in distributor mechanisms forming a part of such engines, reference being made to my co-pending application Serial No. 455,483, entitled Breaker Point Assembly for Internal Combustion Engines, filed September 13, 1954, and my copending application Serial No. 481,990, entitled Breaker Point Apparatus, filed January 17, 1955.

It is the principal object of this invention to provide a breaker point assembly wherein adjustment of dwell time of the electrical contacts of the assembly in their make condition can be carried out with greater precision and wherein such adjustment of dwell time is rendered independent of jitter or vibration in the distributor cam resulting from wear of the journaling for the cam shaft.

It is another important object of this invention to provide a breaker point assembly wherein wear upon the cam engaging and other portions of the apparatus may be fully and accurately compensated for by a single, simple adjustment.

It is another important object of this invention to provide a breaker point assembly for use in connection with a distributor mechanism having a rotatable cam and a a pivot pin in spaced parallelism thereto of reciprocable contact actuating structure having cam follower operating means carried upon a member swingably mounted upon the pivot post, there being adjustable means also carried by the member for engaging the cam oppositely to the zone of engagement therewith of the contact operating means.

Still other important objects of this invention, including certain important details of construction, will be made clear or become apparent as the following description of the invention progresses. Referring now to the accompanying drawing:

Fig. 1 is a top plan view of a conventional distributor having the breaker point assembly of this invention mounted in operative position therewithin;

Fig. 2 is a cross sectional view taken on line IIII of Fig. 1;

Fig. 3 is a cross sectional view taken on line III-III of Fig. 1; and

Fig. 4 is a cross sectional view taken on line IV-IV of Fig. 1.

In the drawing the numeral generally designates a conventional type distributor mechanism having a base 12, a straight, elongated pivot pin 14 extending laterally from base 12, a rotatable shaft 16 extending from base 12 in spaced parallelism to pin 14, and a polygonal cam 18 carried by shaft 16 for rotation therewith. Cam 18 is provided with a peripheral cam surface comprised of a number of spaced, raised points 20 separated by fiat cam surfaces 22, the usual configuration of cam 18 being hexagonal.

A plate-like member 24, which is preferably annular as illustrated, has a central aperture 26 therein for clearing cam 18 and is also provided with a round opening 2,735,905 Patented Feb. 21, 1956 28 and an elongated slot 30. Opening 28 is adapted to receive pin 14 therethrough for pivotal mounting of member 24 upon pin 14. A screw or the like generally designated 32 is provided with a head portion 34 of greater diameter than the lateral dimension of elongated slot 30 and with a threaded portion 36 which may be threadably fastened within one of the mounting holes 38 conventionally provided in the base 12 of standard distributor mechanisms 10. As will be clear from Fig. 4, the threaded portion 36 of screw 32 is of suflicient length that head portion 34 thereof does not restrain swinging movement of member 24 relative to pin 14 until a certain angle of swinging movement has occurred bringing one of the ends of slot 30 into engagement with threaded screw portion 36. The longitudinal axis of slot 30 is so disposed Within member 24 as to permit such limited swinging movement of the latter relative to pin 14, the function of screw 32 being to limit the degree of such swinging movement and, perhaps more important, to retain the member 24 in flat engagement with base 12 of distributor mechanism 10. Obviously, additional slots and screws or the like such as 30 and 32 could be provided in other parts of the member 24, if desired. The member 24 is thus held upon base 12 in such manner as to permit limited swinging movement thereof relative to pin 14 and accordingly cam 18.

A breaker point device generally designated 40 is mounted upon member 24 in any suitable fashion as by a number of screws 42 countersunk within member 24 and threaded into a main body portion 44 of device 40, as best shown in Fig. 2. Device 40 could be of any suitable type having reciprocable contact means such, for instance, as that hereinafter more fully described, and swingable cam follower means engageable with cam 18 for actuating the reciprocable contact means, as will also be hereinafter illustratively more fully explained.

I11 the currently preferred embodiment of this invention, however, device 40 is essentially of the same type as that disclosed in my above-identified co-pending application filed concurrently herewith. Such device 40 has an elongated, cylindrical bore 46 formed in the main body portion 44 of device 40, there being a rod generally designated 48 reciprocably mounted within bore 46 and normally extending from both ends of the latter. Rod 48 preferably has a section of enlarged diameter 40 slidably received by bore 46, a length 52 of smaller diameter extending beyond the opposite end of bore 46, and a portion 54 of further reduced diameter which is crimped as at 56 upon a movable, annular contact plate-like disc 58, which is preferably formed of silver or other highly conductive material. A connection lug 60 is disposed between contact disc 58 and crimped portion 56 of rod 48, disc 58 thereby being firmly held by rod 48 for reciprocation therewith. A conductor wire 62 is connected with lug 60 for providing electrical connection with contact disc 58. A preferably rectangular, stationary contact plate 64, also of silver or other highly conductive material, is rigidly mounted upon main body portion 44 of device 40 in underlying relationship to contact disc 58 by means of a number of screws or the like 66 passing through plate 64 and threaded within main body portion 44. A connection lug 65 is provided on one of the screws 66, and such lug 65 is in turn provided with a conductor wire 67 for making electrical connection with the plate 64. Plate 64 is provided with an opening 68 of sufiicient diameter to clear length 52 of rod 48 without electrically contacting the same. A washer 70 of insulating material is disposed within bore 4 and in underlying relationship to plate 64. A coil spring 72 oppositely bears against washer 70 and enlarged portion 50 of rod 48 to thereby yieldably bias rod 48, and accordingly contact disc 48, in a direction for moving contact disc 58 into engagement with contact plate 64. A cam follower extension 74 is preferably integrally formed with main body portion 44 of device and extends in normally spaced relation between the end of bore 46 from which rod portion 50 emerges and the cam 18, when the device is installled inoperative position within the distributor mechanism 10, as will be most clear in Fig. 1. Cam follower extension 74 preferably includes a pointed, cam engaging protuberance '76. The main body portion 44, cam fo'llower extension 74, and washer are all preferably formed of nylon plastic material, main body portion 44 and extension 74 being, as above noted, preferably a unitary body of such easily workable, wear resistant nylon material. It may be noted that extension 74 is inter connected with main body portion 44' by a section 76 of reduced thickness which, in view of the other properties of the nylon plastic material, is sufficiently flexible to render cam follower extension 74 adapted for continuous, alternate swinging toward and away from main body portion 44 as protuberance 76 alternately engages points 20 and flat surfaces 22 of cam 18.

It will be clear that spring 72 biases rod portion 56 into engagement with cam follower extension 74 thereby urging protuberance 76 of the latter into continuous engagement with cam 18, it being noted that the dimensioning is such that when protuberance 76 is riding upon afiat portion 22 of cam 18, the contact disc 58 will be intight engagement with contact plate 64, and that when protuberance 76 rides over a point 20 of cam 18, contact disc 58 is moved out of contacting engagement with plate 64. The electrical connection between contacts 58 and 64 is, therefore, alternately made and broken a's cam 18- rotates.

It will be appreciated upon a viewing of Pig. 1 that the dwell time of the device 40, or the period that contact 58 remains in engagement with contact 64, depends upon the length and positioning of the flat surface 22. of cam 18, and that same is somewhat critical. It is not surprising, therefore, that in the distributor mechanisms 10 of older engines wear of the journaling for shaft 16 or the like may permit a certain amount of undesired play or jitter in the rotational axis of shaft 16 and cam 18. This results in inaccuracies or inconsistencies in dwell time and renders the precise adjustment of same with conventional breaker point assemblies impossible.

In order to overcome this difficulty, the above-described pivotal mounting for member 24is used and there is provided structure generally designated by the numeral 8% for bearing against that side of cam 18 opposite to proturberance 76, which structure is mounted upon member 24 in such manner as to maintain device 40, and particularly protuberance 76" thereof, in the same relative disposition with respect to the axis of rotation of cam 18 regardless of shifting of the latter.

Structure 80 preferably includes a block' 82 of nylon plastic material rigidly mounted upon member 24 by meansof countersunk screws or the like 84', such main block or body portion 82 of structure Stlbeing provided with a cam follower element 86 having a cam engaging protuberance 88. Block 82 and cam follower element 86'may have substantially the same configuration as that above described for main body portion 44 and cam follower extension 74 of device 40, except that block 82 is provided with a threaded bore 90 in which is threadably fitted a bolt or the like 92 having an end 94' in engagement with cam follower element 86. A lock nut 96 is preferably provided upon bolt 92.

It will be clear that by threadable adjustment of bolt 92 within block 82 the follower element 86, and accordingly protuberance 88 thereof may be moved either toward or away from the direction-of cam 38. Since protuberance '76 under the influence of spring 72 is bearing upon cam 18 oppositely to protuberance 8 8 of structure 8%, itwill be clear that as bolt 92 is adjusted the member 24 will pivot about pin 14 in the direction dictated by the movement of bolt 92. In this fashion, the pressure upon protuberance 76 or, perhaps more accurately, the relative positioning of same with respect to the axis of rotation of cam 18 will obviously be maintained constant, since member 24 will be free to pivot about pin 14- under the influence of structure 80 should the axis of rotation of cam 18 shift. It will also be apparent that merely by adjustment of the bolt 92 full compensation can be made for any wear that occurs upon protuberances 76 and 83 or the opposed contact faces of disc 58 and plate 64. Thus, by a single, simple adjustment, the dwell time for device 41) can be precisely adjusted for any condition of Wear of the distributor mechanism 19 or the working parts of the assembly of this invention.

It will, therefore, be apparent that the combination of structure above described is ideally suited for accomplishing the desirable and advantageous results sought by this invention as above recited in the objectives thereof. it will be equally clear, however, that certain minor modifications and changes could be made from the exact, preferred construction disclosed without materially departing from the true spirit and intention of the invention. Accordingly, it is to be understood that this invention shall be deemed limited only by the scope of the appended claims. I I

Having thus described the invention, what is claimed a'snew and desired to be secured by Letters Patent is:

l. A breaker point assembly for use with an internal combustion engine having a distributor mechanism conventionally including a base, a pivot pin extending from the base, a rotatable shaft extending from the base spaced parallelism to the pin and a cam carried on the shaft, said assembly comprising, in combination, a rigid member adapted to be pivotally mounted on said pin; an unyielding element mounted on the member and adapted to engage said cam when the member is so mounted on the pin; a breaker point device mounted on the member and having a stationary contact, whose position is fixed relative to the member, a movable contact whose position is shiftable relative to the member and shiftable structure adapted to engage said cam oppositely to the Zone of engagement of the element therewith when the member is so mounted on the pin, said structure being operably coupled with the movable contact for shifting the latter to and from a position in engagement with the stationary contact as said cam is rotated; and means yieldably biasing said structure toward said earn.

2. A breaker point assembly for use with an internal combustion engine having a distributor mechanism conventionally including a base, a pivot pin extending from the base, a rotatable shaft extending. from the base in spaced parallelism to the pin and a cam carried on the shaft, said assembly comprising, in combination, a member adapted to be pivotally mounted on said pin; an element mounted on the member and adapted to engage said cam when the member is so mounted on the pin; a breaker point device mounted on the member and having a stationary contact, a movable contact and shiftable structure adapted to engage said cam oppositely to the zone of engagement of the element therewith when the member is so mounted on the pin, said structure being operably coupled with the movable contact for shifting the latter to and from a position in engagement with the stationary contact as said cam is rotated; and means yieldably biasing said structure toward said cam, said member comprising an annular plate having a central aperture adapted to clear said shaft and cam, and anopening adapted to pivotally receive said pin.

3. A breaker point assembly for use with an internal combustion engine having a distributor mechanism conventionaily including a base, a pivot pin extending from the base, a rotatable shaft extending from the base in spaced parallelism to the pin and a cam carried on the shaft, said assembly comprising, in combination, a member adapted to be pivotally mounted on said pin; an

element mounted on the member and adapted to engage said cam when the member is so mounted on the pin; a breaker point device mounted on the member and having a stationary contact, a movable contact and shiftable structure adapted to engage said cam oppositely to the zone of engagement of the element therewith when the member is so mounted on the pin, said structure being operably coupled with the movable contact for shifting the latter to and from a position in engagement with the stationary contact as said cam is rotated; means yieldably biasing said structure toward said cam; and means for limiting the pivotal movement of the member about said pin.

4. A breaker point assembly for use with an internal combustion engine having a distributor mechanism conventionally including a base, a pivot pin extending from the base, a rotatable shaft extending from the base in spaced parallelism to the pin and a cam carried on the shaft, said assembly comprising, in combination, a member adapted to be pivotally mounted on said pin; an element mounted on the member and adapted to engage said cam when the member is so mounted on the pin; a breaker point device mounted on the member and having a stationary contact, a movable contact and shiftable structure adapted to engage said cam oppositely to the zone of engagement of the element therewith when the member is so mounted on the pin, said structure being operably coupled with the movable contact for shifting the latter to and from a position in engagement with the stationary contact as said cam is rotated; and means yieldably biasing said structure toward said cam, said element being adjustably shiftable relative to the member toward and away from the direction of said cam.

5. A breaker point assembly for use with an internal combustion engine having a distributor mechanism conventionally including a base, a pivot pin extending from the base, a rotatable shaft extending from the base in spaced parallelism to the pin and a cam carried on the shaft, said assembly comprising, in combination, a member adapted to be pivotally mounted on said pin; an element mounted on the member and adapted to engage said cam when the member is so mounted on the pin; a breaker point device mounted on the member and having a stationary contact, a movable contact and shiftable structure adapted to engage said cam oppositely to the zone of engagement of the element therewith when the member is so mounted on the pin, said structure being operably coupled with the movable contact for shifting the latter to and from a position in engagement with the stationary contact as said cam is rotated; and means yieldably biasing said structure toward said cam, said device including a body having a bore therein, an elongated rod reciprocably mounted in the bore and carrying said movable contact on one end thereof, said structure comprising a wear-resistant, swingable extension on the body and extending between the other end of the rod and the cam, and said means comprising a spring biasing the rod in the direction of the extension.

6. A breaker point assembly for use with an internal combustion engine having a distributor mechanism conventionally including a base, a pivot pin extending from the base, a rotatable shaft extending from the base in spaced parallelism to the pin and a cam carried on the shaft, said assembly comprising, in combination, a member adapted to be pivotally mounted on said pin and having branches adapted to extend around opposite sides of said cam when the member is so mounted on said pin; an element shiftably mounted on one of said branches for adjustment relative to the member toward and away from the direction of said cam and adapted to engage said cam when the member is so mounted on said pin; a body having an elongated bore therethrough mounted on the other of said branches with the longitudinal axis of the bore disposed substantially perpendicular to the aXis of rotation of the cam; an elongated rod reciprocably mounted in the bore and normally extending beyond both ends of the latter; a first electrical contact mounted on the end of the rod remote from said cam when the member is so mounted on said pin and reciprocable with the rod; a second electrical contact mounted on the body and thereon disposed for engagement by the first contact when the rod is reciprocated in one direction toward said cam when the member is so mounted on said pin; a swingable extension on said other branch adapted to extend between the other end of the rod and said cam and to be oppositely engaged thereby when the member is so mounted on said pin; and spring means yieldably biasing the rod in the direction of the extension.

References Cited in the file of this patent UNITED STATES PATENTS 

